What primary sources prove that Lord (Count) of Ghent Theodric de Gand van Hamaland Hildegarde van Hamaland Wichman III van Gent Lambert Wichman van Gent
are also the children of Wichmann IV (V) van Hamaland, graaf van Gent en Hamaland & Liutgard van Vlaanderen
No sources are provided, and Medlands has proof of only 2 daughters: Adela 'de Wrede', von Hamaland & Liutgard van Hamaland
cf http://fmg.ac/Projects/MedLands/HOLLAND.htm#WichmannHamalanddiedaft...
Will reconnect once primary sources are provided.
Not a primary source of course, but the Dutch and German versions of Wikipedia do both mention a son Wichman, who died before being 10 years old. The German version mentions another son Meginhard but admits his existence is not certain.
Anyway, Wichmann IV (V) van Hamaland, graaf van Gent en Hamaland died without a male heir